At the end of this section you should be able to:

1. Properly apply normal- and friction forces onto FBDs with interacting surfaces

   • Write proper equilibrium equations from the FBDs

2. Find at what point a system will be on the verge of motion (from an applied force, moment, etc.)

   • Create additional sets of equations based on objects possibly slipping or tipping

3. Determine if a system will be in motion or equilibrium under given parameters and conditions

This section teaches how to model dry friction and analyze impending motion in statics. You will place normal forces and friction forces correctly on free body diagrams for contacting surfaces, write equilibrium equations from those diagrams, and apply the limiting friction condition to find the applied force or moment that brings a system to the verge of slipping or tipping. You will practice cases with multiple possible slip directions, blocks on inclined planes, ladders against walls, motion on surfaces defined by functions, sliding and rotating contacts, and self-locking mechanisms, and you will learn how to check whether a system remains in equilibrium or must move for a given set of parameters. Mathematica resources are included to help set up and solve the resulting equation sets.